1. Field of the Invention
The present invention relates to a housing case for an electronic circuit board, more particularly to a housing case for an electronic circuit board provided with a pair of guide rails that form a guide path for guiding the electronic circuit board.
2. Description of the Related Art
Conventionally, the housing cases for housing the electronic circuit boards on which connectors, electronic parts and other components are integrally mounted or fixed are configured such that the electronic circuit board can be easily inserted and fixed at a predetermined position in the housing case, as disclosed, for example, in Japanese Laid-Open Patent Application No. 2001-237557 (from paragraph 0031 to 0034, FIG. 1, etc.).
Specifically, in the technique taught in '557, the connectors are fixed on the electronic circuit board by soldering the distal portions of connection terminals of the connectors on the board, and two rails are formed so as to face each other on the internal wall surface of the housing case in which the electronic circuit board is to be inserted. In addition, flange-like projections are formed on the surfaces of the connectors that are in contact with the housing case (i.e., surfaces opposite to the surface facing the electronic circuit board), and recesses are formed in the housing case for engagement with the projections.
When the electronic circuit board is inserted between the rails and fixed at a predetermined position in the housing case, the projections engage the recesses. The electronic circuit board is thereby easily inserted and accurately fixed at a predetermined position in the housing case.
However, at a time when the electronic circuit board is housed in the housing case taught in '557, when mating connectors are to be inserted or removed from the connectors mounted on the electronic circuit board, it produces a twisting/shaking force that will then be applied or transmitted to the electronic circuit board.
Since the spacing (groove width) of the rails holding the electronic circuit board is substantially the same as the thickness of the electronic circuit board (more precisely equal to the board thickness plus about 0.1 mm), the electronic circuit board can hardly move in the direction in which the twisting/shaking force acts, whereby the twisting/shaking force concentrates at the joints (soldered portions) where the components such as connectors are joined to the electronic circuit board. The twisting/shaking force disadvantageously acts to increase the stress on the joints, thereby rendering the electrical connections between the connectors and the electronic circuit board unstable.